CMUcam1 baud rate problem

k_ishan

hello......
i am doing project on "transmission of images from a robot to a computer or laptop".
i am using CMUcam for capturing images.
CMUcam can transmit image data through USART with only 115200, 38400 and 9600 baud rates.
After capturing image i want to transmit this data by using RF tranciever module.
RF module i am using is also having USART interface. But RF module i am working with works with baud rates only less than 9600.
Thus i want to communicate a camera whose baud rate is greater than 9600 with a RF tranciever whose baud rate is less than 9600.
so can u please suggest some method/ programme which will make CMUcam to transmit data with lower baud rates(less than 9600)
so please please suggest some solution to this problem......

Mike Green

You will need some way to receive a complete image from the CMUcam at 9600 Baud, temporarily store the image in some kind of buffer, then re-transmit the image at a lower Baud, suitable for the RF transceiver. How you do this depends on the size of the image. This would be done with a microcontroller and a memory large enough for an image. You've posted your question on the Stamp forum, but a Stamp is really not suitable for this in that it has very little memory available for storing an image and the BS2 Stamp is really marginal at 9600 Baud. You could use a Propeller for this. The size of the image will determine whether you'd need to provide some kind of additional memory. The Propeller's built-in memory is 32K, but it's easy to add external memory for use as a buffer.

Mike Green

1) Please do not cross-post (post essentially the same question in more than one forum). It is not allowed.

2) You cannot make the CMUcam1 transmit with lower Baud (less than 9600). It is not designed for that. There are comments in the documentation that some of the board's functions do not work as well even at 9600 Baud. Theoretically, you could request the firmware source code from CMU, modify it to allow for Bauds less than 9600, and reprogram the SX processor on the board. Practically speaking, this is not doable and we can't help you with it. Sorry.

3) See my post #2. Some kind of "smart" external buffer is really the only way to do this. Given the resolution of the camera, it looks like the buffer size would need to be a little over 8K in size. The Propeller could certainly do this and you'd need to write a Propeller program to handle the commands to the CMUcam1 and the data packets from it.